This invention relates to electret filters, more particularly, to electret filters that have high trapping capability, with the added advantage that their ability to trap cigarette smoke is retained in a consistent manner.
Electret filters are used as filter media in many applications such as home and industrial air conditioners, air cleaners, vacuum cleaners, fan heaters and air conditioning systems for common equipment to clean ambient atmospheres by trapping the dust, smoke and other particulate contaminants. Such electret filters are conventionally prepared from nonwoven fabrics of polymers such as polypropylene by processing them into electrets. However, the conventional electret filters have had the problem that they are not highly suitable for adsorbing cigarette smoke since their ability to trap it will drop markedly with the amount of adsorption and cannot be retained in a consistent manner.